diff --git a/config/database.go b/config/database.go
new file mode 100644
index 0000000..2708d1c
--- /dev/null
+++ b/config/database.go
@@ -0,0 +1,20 @@
+package config
+
+import "github.com/caarlos0/env"
+
+type DatabaseConfig struct {
+	Debug        bool   `env:"DB_DEBUG" envDefault:"false"`
+	DatabaseType string `env:"DB_TYPE,required"`
+	Host         string `env:"DB_HOST,required"`
+	Port         int    `env:"DB_PORT"`
+	Username     string `env:"DB_USER"`
+	Password     string `env:"DB_PASS"`
+	Database     string `env:"DB_DATABASE"`
+}
+
+func (dc *DatabaseConfig) LoadConfig() error {
+	if err := env.Parse(dc); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/go.mod b/go.mod
index 45596e2..8c6088a 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,9 @@
 module git.dragon-labs.de/alphyron/group_helper
 
 go 1.13
+
+require (
+	github.com/caarlos0/env v3.5.0+incompatible
+	github.com/jinzhu/gorm v1.9.12
+	github.com/stretchr/testify v1.5.1 // indirect
+)
diff --git a/logic/repository.go b/logic/repository.go
new file mode 100644
index 0000000..79b58fe
--- /dev/null
+++ b/logic/repository.go
@@ -0,0 +1,6 @@
+package logic
+
+type GroupHelperRepository interface {
+	GroupHelperService
+	InitRepository() error
+}
diff --git a/logic/service.go b/logic/service.go
index ba6c3cd..aa45c29 100644
--- a/logic/service.go
+++ b/logic/service.go
@@ -7,10 +7,10 @@ type GroupHelperService interface {
 	UpdateGroup(*models.Group) (*models.Group, error)
 
 	GetGroupByID(int64) (*models.Group, error)
-	GetGroupDatabaseSize(int64) (int, error)
+	GetGroupDatabaseSize(*models.Group) (int, error)
 
 	CreateUser(*models.User) (*models.User, error)
-	GetUserByID(int64) *models.User
+	GetUserByID(int64) (*models.User, error)
 
 	UserJoinGroup(*models.User, *models.Group) (bool, error)
 	UserLeaveGroup(*models.User, *models.Group) (bool, error)
diff --git a/main.go b/main.go
index 081abb2..43943ac 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,15 @@
 package main
 
-import "log"
+import (
+	"git.dragon-labs.de/alphyron/group_helper/config"
+	"log"
+)
 
 func main() {
-	log.Println("Hello World")
+	err := config.DatabaseConfig{}.LoadConfig()
+
+	if err != nil {
+		log.Println("Problem while loading database environment variables")
+		log.Fatal(err)
+	}
 }
diff --git a/models/group.go b/models/group.go
index 09ad143..8a2543b 100644
--- a/models/group.go
+++ b/models/group.go
@@ -4,12 +4,13 @@ type Group struct {
 	ID                  uint `gorm:"primary_key"`
 	GroupID             int64
 	Size                int
-	UserJoinMessage     string `gorm:"column:msg_user_join;type:text"`
-	UserVerifiedMessage string `gorm:"column:msg_user_verified;type:text"`
-	UserLeaveMessage    string `gorm:"column:msg_user_leave;type:text"`
-	UserKickMessage     string `gorm:"column:msg_user_kick;type:text"`
-	ForbidWriting       bool   `gorm:"column:forbid_writing"`
-	OnlineCheck         int    `gorm:"column:kick_cooldown"`
+	UserJoinMessage     string  `gorm:"column:msg_user_join;type:text"`
+	UserVerifiedMessage string  `gorm:"column:msg_user_verified;type:text"`
+	UserLeaveMessage    string  `gorm:"column:msg_user_leave;type:text"`
+	UserKickMessage     string  `gorm:"column:msg_user_kick;type:text"`
+	ForbidWriting       bool    `gorm:"column:forbid_writing"`
+	OnlineCheck         int     `gorm:"column:kick_cooldown"`
+	Users               []*User `gorm:"many2many:GroupUser;"`
 }
 
 func (group *Group) FillDefaultValues() {
diff --git a/repository/grouphelperrepository.go b/repository/grouphelperrepository.go
new file mode 100644
index 0000000..c3a7eb8
--- /dev/null
+++ b/repository/grouphelperrepository.go
@@ -0,0 +1,18 @@
+package repository
+
+import (
+	"errors"
+	"git.dragon-labs.de/alphyron/group_helper/config"
+	"git.dragon-labs.de/alphyron/group_helper/logic"
+)
+
+func NewUserHelperRepository() (*logic.GroupHelperRepository, error) {
+	databaseConfig := config.DatabaseConfig{}
+	_ = databaseConfig.LoadConfig()
+
+	switch databaseConfig.DatabaseType {
+
+	}
+
+	return nil, errors.New("cannot support given database type (" + databaseConfig.DatabaseType + ")")
+}
diff --git a/repository/sql/grouphelprepository.go b/repository/sql/grouphelprepository.go
new file mode 100644
index 0000000..2346f14
--- /dev/null
+++ b/repository/sql/grouphelprepository.go
@@ -0,0 +1,186 @@
+package sql
+
+import (
+	"errors"
+	"fmt"
+	"git.dragon-labs.de/alphyron/group_helper/config"
+	"git.dragon-labs.de/alphyron/group_helper/logic"
+	"git.dragon-labs.de/alphyron/group_helper/models"
+	"github.com/jinzhu/gorm"
+	_ "github.com/jinzhu/gorm/dialects/mssql"
+	_ "github.com/jinzhu/gorm/dialects/mysql"
+	_ "github.com/jinzhu/gorm/dialects/postgres"
+	_ "github.com/jinzhu/gorm/dialects/sqlite"
+)
+
+type groupHelperRepository struct {
+	Conn *gorm.DB
+}
+
+func newMySQLConnection(host string, database string, user string, password string) (*gorm.DB, error) {
+	return gorm.Open("mysql", fmt.Sprintf("%s:%s@(%s)/%s?charset=utf8mb4&parseTime=True&loc=Local", user, password, host, database))
+}
+
+func newPostgresConnection(host string, port int, database string, user string, password string) (*gorm.DB, error) {
+	return gorm.Open("postgres", fmt.Sprintf("host=%s port=%d user=%s dbname=%s password=%s", host, port, user, database, password))
+}
+
+func newSQLiteConnection(path string) (*gorm.DB, error) {
+	return gorm.Open("sqlite3", path)
+}
+
+func newMsSqlConnection(host string, database string, user string, password string) (*gorm.DB, error) {
+	return gorm.Open("mssql", fmt.Sprintf("sqlserver://%s:%s@%s?database=%s", user, password, host, database))
+}
+
+// NewUserRepository tamdp, test
+func NewGroupHelperRepository(config *config.DatabaseConfig) (logic.GroupHelperRepository, error) {
+	var (
+		db  *gorm.DB
+		err error
+	)
+
+	switch config.DatabaseType {
+	case "mysql":
+		db, err = newMySQLConnection(fmt.Sprintf("%s:%d", config.Host, config.Port), config.Database, config.Username, config.Password)
+		break
+	case "postgres":
+		db, err = newPostgresConnection(config.Host, config.Port, config.Database, config.Username, config.Password)
+		break
+	case "sqlite3":
+		db, err = newSQLiteConnection(config.Host)
+		break
+	case "mssql":
+		db, err = newMsSqlConnection(fmt.Sprintf("%s:%d", config.Host, config.Port), config.Database, config.Username, config.Password)
+		break
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	if db == nil {
+		return nil, errors.New("no valid type given (mysql,postgres,sqlite3,mssql)")
+	}
+
+	db.LogMode(config.Debug)
+	return &groupHelperRepository{Conn: db}, nil
+}
+
+// NewUserRepositoryDBConnection creates a user repository with an existing gorm database connection
+func NewUserRepositoryDBConnection(db *gorm.DB) logic.GroupHelperRepository {
+	return &groupHelperRepository{Conn: db}
+}
+
+func (g groupHelperRepository) CreateGroup(group *models.Group) (*models.Group, error) {
+	err := g.Conn.Create(group).Error
+
+	if err != nil {
+		return nil, errors.New("problem while creating a group - " + err.Error())
+	}
+
+	return group, nil
+}
+
+func (g groupHelperRepository) UpdateGroup(group *models.Group) (*models.Group, error) {
+	err := g.Conn.Where("id = ?", group.ID).Save(group).Error
+	return group, err
+}
+
+func (g groupHelperRepository) GetGroupByID(id int64) (*models.Group, error) {
+	var group models.Group
+	err := g.Conn.Where("group_id = ?", id).First(&group).Error
+
+	if err != nil {
+		return nil, errors.New("problem while getting the group by his group id - " + err.Error())
+	}
+	return &group, nil
+}
+
+func (g groupHelperRepository) GetGroupDatabaseSize(group *models.Group) (int, error) {
+	association := g.Conn.Model(group).Association("Users")
+
+	if err := association.Error; err != nil {
+		return -1, errors.New("problem while getting the size of users connected with the group - " + err.Error())
+	}
+
+	return association.Count(), nil
+}
+
+func (g groupHelperRepository) CreateUser(user *models.User) (*models.User, error) {
+	err := g.Conn.Create(user).Error
+
+	if err != nil {
+		return nil, errors.New("problem while creating a user - " + err.Error())
+	}
+
+	return user, nil
+}
+
+func (g groupHelperRepository) GetUserByID(userID int64) (*models.User, error) {
+	var user models.User
+	err := g.Conn.Where("user_id = ?", userID).First(&user).Error
+
+	if err != nil {
+		return nil, errors.New("problem while getting the user by his user id - " + err.Error())
+	}
+	return &user, nil
+}
+
+func (g groupHelperRepository) UserJoinGroup(user *models.User, group *models.Group) (bool, error) {
+	err := g.Conn.Model(user).Association("Groups").Append(group).Error
+
+	if err != nil {
+		return false, errors.New("problem while connect the user with the group - " + err.Error())
+	}
+	return true, nil
+}
+
+func (g groupHelperRepository) UserLeaveGroup(user *models.User, group *models.Group) (bool, error) {
+	err := g.Conn.Model(user).Association("Groups").Append(group).Error
+
+	if err != nil {
+		return false, errors.New("problem while disconnecting the user from the group - " + err.Error())
+	}
+	return true, nil
+}
+
+func (g groupHelperRepository) IsUserInGroup(user *models.User, group *models.Group) (bool, error) {
+	association := g.Conn.Model(user).Association("Groups")
+
+	if err := association.Error; err != nil {
+		return false, errors.New("problem while checking if the user is connected with the group - " + err.Error())
+	}
+
+	association = association.Find(group)
+
+	if err := association.Error; err != nil {
+		return false, errors.New("problem while find the user is connected with the group - " + err.Error())
+	}
+
+	return association.Count() > 0, nil
+}
+
+func (g groupHelperRepository) ListGroups() ([]*models.Group, error) {
+	var groups []*models.Group
+	err := g.Conn.Find(&groups).Error
+
+	if err != nil {
+		return nil, errors.New("problem while getting all group - " + err.Error())
+	}
+	return groups, nil
+}
+
+func (g groupHelperRepository) ListUsers() ([]*models.User, error) {
+	var users []*models.User
+	err := g.Conn.Find(&users).Error
+
+	if err != nil {
+		return nil, errors.New("problem while getting all users - " + err.Error())
+	}
+	return users, nil
+}
+
+func (g groupHelperRepository) InitRepository() error {
+	return g.Conn.AutoMigrate(models.Group{}, models.User{}).Error
+}